Our work in the first five years of the Multicenter has demonstrated that early focal brain injury does result in specific and persistent deficits of linguistic and cognitive functioning. These data have made substantial contributions to the growing body of data showing that even very early in development the brain is not equipotential for all functions. However, also consistent with other recent data, the specific patterns of deficit we have observed do not map precisely to those observed in adults with comparable injury. Early deficits are less severe and the association between deficit and lesion site is more varied. These findings suggest that plasticity may still play a significant role in early brain and behavioral development. The purpose of this project is to map more precisely relations between brain and behavioral in development. Detailed accounts of the development of cognitive and linguistic functioning, in concert with prospective studies of brain function, brain structure, and sensory-motor processing will be crucial to our understanding of this issue. In Years 6 - 10, we will explore these changes in brain-behavior relations through detailed accounts of the development of cognitive and linguistic functioning, with specific focus on the transition from the preschool to the school years. This focus will allow us to address more fully issues concerned with functional recovery. In addition, we will extend our range of inquiry to include several areas of development not explored in the first phase of the multicenter. Our interactions with the children in the first phase of the project have alerted us to possible areas of selective deficits in the domains of selective attention, reasoning and affective production and comprehension. In the next phase of the project we will begin a systematic investigation of development in these domains. The experiments presented in this proposal all focus on the study of behavior in the focal lesion population. In the second phase of the project, specification of deficit and recovery of function remain the overarching issues which shape and guide the work. Within that broad framework, we propose a series of more specifically targeted hypotheses. This series of hypotheses fall roughly into three levels which correspond to the theoretical goals and utilize the analytic strategies outlined for the Center as a whole: Identification of specific deficits of cognitive and linguistic functioning, cross-domain comparisons examining similarities and differences in developmental trajectories, and cross-population comparison.